An exemplary resin multilayer substrate including a rigid part and a flexible part is described in Japanese Patent Laying-Open No. 2004-158545 (PTD 1). In PTD 1, a configuration in which the rigid part and the flexible part have different flexibilities is achieved by laminating a larger number of resin films in the rigid part and laminating a smaller number of resin films in the flexible part when the resin films are laminated to manufacture a multilayer substrate. In the configuration shown in PTD 1, a semiconductor element is built-in in the middle of the rigid part.